Effect of three-component microbial inoculant on winter rye and spring barley yields

One of the modern techniques of improving microbial preparations efficiency is a combination of several microorganisms with different beneficial properties in one inoculant. Taking into account the role of nitrogen and potassium nutrition and their synergism, it is essential to develop preparations of N2-fixing and K-mobilizing rhizobacteria, especially Azospirillum sp. and Bacillus sp. Effective biological control of root infections is of great importance in order to prevent crop yield losses. Among soil antagonistic fungi, Trichoderma sp. is the most promising one. Microbial inoculant includes three components: Azospirillum brasilеnse 2(b)3 + Bacillus circulans K-81 + Trichoderma longibrachiatum L-7 (1:1:1). Combined application of rhizobacteria A. brasilense + B. сirculans induced significant hormonal effect. Roots dry mass increased by 28%, roots length per plant – by 25%, stem dry mass – by 33%. In the field experiment, the treatment of barley by microbial inoculant provided the reduction of root rot incidence by 52.0–58.0%, disease development (waxy ripeness) – by 2.6–2.9 times, biological efficiency was 66.3–69.5%. Treatment of winter rye resulted in the reduction of disease incidence by 42.4–45.0%, disease development (milky ripeness) – by 2.0–2.6 times, biological efficiency – 50.2–61.2% according to soil-erosion catena. Beneficial influence of inoculation on plant development and nutrition, as well as effective biological control of plant diseases, provided significant crop responses: for winter rye – 3.8-4.5 c ha-1 or 7.0% - 9.8%, for spring barley – 5,2 – 4.9 c ha-1 or 9.3% – 9.2% according to soil-erosion catena. Microbial inoculant exhibits the properties of plant growth promoter, biological fertilizer, and biological fungicide.